MOBILE HOME HEATING - CONTENTS: Mobile home heating & air conditioning system inspection guide
- Common mobile home heating system defects. Mobile home cooling system and ductwork defects. Mobile home insulation defects and remedies to reduce heating and cooling costs

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Mobile home heating & air conditioning systems:

How to Inspect the heating and cooling systems in mobile homes, trailers, double-wides, multi-wides:

How to spot common and dangerous defects in heating equipment incuding furnaces and boilers, inadequate heat distribution, freeze-ups, and safety hazards.

How to save heating or cooling costs for mobile homes and trailers or multi-wides. Page top sketch was provided courtesy of Carson Dunlop Associates, a Toronto engineering, education, and home inspection company.

MOBILE HOME HEATING System Defects

General Characteristics:

Hot air, gas-fired, central return heating units are most common ; oil & electric mobile home furnace-heaters are also used;

20% of mobile homes have problems with HVAC (C. r. survey);

[Click to enlarge any image]

Question: I was startled out of my skin to see a cat jump into the living room from a floor vent

(Aug 29, 2012) Maxine Payne said:

The red tag was apparently covered up when vinyl siding was installed. Now I want to sell the property, but I can't because I do not have the red tag number. How do I get the red tag number?

(Aug 29, 2012) Greg Filian said:

The flashing of the lights mentioned are they in the whole house or just one outlet? If it's just one outlet it may be just the outlet, if it's the whole house the problem may be at the main connection.

(Sept 8, 2012) Gail said:

I am looking at buying a double wide through an estate sale. The "trustee" of the estate is the deceased owners daughter, who know very little to anything about mobile homes (as I).

I am hiring an inspector, how ever he wont be available for 3 weeks and I have an immediate concern...
While standing in the living room I was startled out of my skin to see a cat jump into the living room from a floor vent ( vent cover was pulled off) I looked into the vent and it appears to be completley open - no duct work - just a view of the ground beneath. The daughter said that that was common and is there for ventilation. LOL Tell me this isnt so!

Reply:

Gail,
Thank you SO much for the wonderful cat - HVAC system question.

Yes I can tell you "it isn't so" - that is, it is not good practice to simply leave floor vents in a home open to the outdoors such that anything, including a cat (or worse, a raccoon) can hop in for a visit.

I can imagine a few reasons why you might have found the missing duct work and open floor vent, all adding up to some more trouble and work for you. For example most likely there was a heating or heating and cooling system that used air but that has disintegrated, been damaged, fallen off, or was simply removed and abandoned.

Sometimes too, when warm or cool air delivery into a home is poor in flow rate or quantity, people try to improve system operation by adding more return air to the system by just cutting an opening that lets outdoor air into the system somewhere. The problem is this is the most expensive possible way to heat or cool a home since it's a "one way" design - we take un-conditioned air from outside, heat it or cool it, then try moving it into the living area.

Really the most significant implication of the cat in the hat, I mean cat in the vent discovery in your possible future home's heating sysem is that it's a red flag to watch out for other work done or "problems solved" by the same person on that home - as you may find other amateur workmanship that lengthens the list of repairs and improvements needed to make the home safe and habitable to normal standards.

Keep me posted, and send along photos if you can (use the CONTACT US link at page bottom or top) - especially if ... the cat comes back.

Daniel Friedman

I suppose a less ridiculous explanation that the owner could have invented might have been to explain

"Oh I forgot to tell you, that's just Marion, my mom's cat. Marion comes with the house. The hole in the floor is her pet door."

Common Defects in Mobile Home Heating Systems

Fuel connection should have label indicating equipment
and piping are ok for natural or LP gas or both; inadequate combustion air

Our photo (above left) shows an oil fired heating flue venting directly through the mobile home side wall and just inches from the home's windows.

Our second photo (above-right) shows a makeshift gas flue using aluminum venting (not recommended, unsafe), a too-short chimney (inadequate draft) and flimsy construction, as well as probably leaks into the home wall over the entry door. Notice the soot around the base of the flue where it penetrates the wall?

Unsafe fire clearances and inadequate working space to maintain heating equipment are not due to the mobile home manufacturer but due to low-budget modifications such as this oil burner access through a bath vanity cabinet door (photo above).

Warm air heat return air in a mobile home: all return air taken from crawl area
beneath living unit - one-way heat; blocked return; blocked supply; ducts
through un-heated area;

NO return air, or none when utility closet door is shut! We see this design too often - it is the most expensive way you could heat your mobile home since none of the interior air is being recycled through the heating furnace.

Mobile home heat safety warning: Our photo of a mobile home warm air furnace (left) shows that someone has put paneling over the door to stop drafts - also cutting off return air to the furnace and possibly making it very dangerous if this step has also cut off combustion air from this heater.

Because the mobile home furnace is shoe-horned into a tight space it is too often the case that the system is not inspected and cleaned on schedule. Generally you will save more on reduced heating costs by having an expert clean and tune the system than you will pay for the service call.

Air filters are often ignored - change the filter monthly when the heating or cooling system are in use. A clogged air filter will reduce air flow from your heater, increasing heating costs as well as making the home less comfortable.

LP Tanks, copper gas lines are often left unsupported and exposed to mechanical
damage; also check for LP gas leaks at tanks or fittings;

Oil tanks at trailers and mobile homes - indoor-rated heating oil tanks are quite often placed outside, above ground,
in ground contact, with heat tapes (a fire hazard), often leaking, and in cold
climates, exposed to frost-risk which in turn risks loss of heat and related damage to the home

Missing or still-covered-over spark arrestor on the heating flue on a mobile home - have your heating service technician check the safety of the entire flue and chimney, including the outside components

Combustion Air Defects & Safety Hazards at Doublewide, Mobile Home or Trailer Home Heating System

Below our photographs illustrate several unsafe conditions at a house trailer's heating system inspected by D Friedman & S Vermilye during a mobile home site safety investigation.

No return air from occupied space to the furnace: Above we notice that when the door to the "furnace closet" in this mobile home is shut, there is no return air movement from the home's heated interior to the furnace - creating the most-expensive possible way to operate the furnace. We call this a "one way" heating system: scrounge some air from a cold outdoor or crawl space source, heat it, and blow it into the living space.

In addition to the absence of return air to the heating furnace we notice that

Dirt blockage of air flow: the return air inlet grille is partly blocked by dust and debris, further reducing air flow, increasing heating cost, and ...

Watch out: there is an increased risk of potentially fatal carbon monoxide poisoning if the system lacks adequate combustion air

Blocked air filter: if an air filter is installed (remains to be discovered), given how dirty is the exterior of this furnace the air filter may be equally dirty and airflow blocked

The leak stains and corrosoion on and below the heating flue indicate that the chimney and flue are leaking, risking hidden damage, leaks, holes, water or rust damage to the furnace heat exchanger: all further pointers to an unsafe heating system

On some of these installations combustion air is provided from outdoors through wall or floor openings in the furnace closet, increasing safety but ignoring operating cost

MOBILE HOME COOLING System Defects - Air Conditioning

Question: Why does my doublewide always feel uncomfortably warm

Why does my doublewide always feel uncomfortably warm especially at night when trying to sleep and even with the temperature at 70 to 71 degrees? - Daniel Phipps 4/16/2012

Reply:

Daniel that question has me stumped. There are so many possible reasons:

- a medical problem
- windows shut
- no ventilation
- bedroom close to a heating appliance that is "on" such as a water heater
- air conditioning system that is not working properly, has a blocked filter, blocked cool air return, dirty blower fan, etc. - see MOBILE HOME COOLING discussed here

Check your own sensations against actual room temperature - I'm not sure if that's what your comment about "even with the temp .." meant.

General Characteristics of Mobile Home Cooling Ducts

Heating or Cooling Ducts placed at one of these typical locations:

cooling ducts placed in the floor along center line of the mobile home;

cooling ducts placed in the in trailer or mobile home ceiling (better cooling in South);

[The duct location may tip off the wind zone rating intended for the mobile home unit being inspected.]

Common Mobile Home / Doublewide HVAC Duct Defects

floor ducts often damaged; registers blocked or covered by carpeting

floor ducts below the home, in an uninsulated space

floor ducts below the home that have

lost their insulation

fallen open

are incomplete

have been invaded by rodents or mol

Question: my homeowners insurance covers "accessible ductwork" from the air conditioning - what does that include?

I have home owners insurance, and it says it covers "accessible ductwork from the air condtioning unit to the point of attachment at register" what does that mean? Is my ductwork under the house covered? - Anonymous 7/17/2012

Reply:

Discussion of "accessible" building components vs inaccessible

Anon: re "accessible ductwork" - indeed that word has been the subject of lots of debate - the final answer lies with your insurance company and perhaps the onsite tech. Generally for building inspectors the term "readily accessible" is used to mean that the component can be approached, seen, touched, without having to cut anything apart or disassemble anything not intended to be opened by a homeowner.

For a service technician, "accessible" means it's reasonably possible to get to it - in my OPINION - without having to cut holes in ceilings, walls, floors. So if "under the house" is an area that can be physically accessed, say by entering a crawl space that is not itself so tight or unsafe as to be not enter-able, then in my OPINION the ducts are accessible.

When we debated this question at a home inspection association it was after an inspector had fallen to his death while crawling up a building-mounted but loose roof access ladder. He felt that he HAD to access the building roof but there was no other means for him to do so. He was killed.

A result of that terrible experience was a decision that ultimately we do not ever want to demand that anyone, inspector, nor service technician, attempt to "access" a building component or area if s/he has a reason for not doing so, such as a personal judgement about safety.

However that doesn't mean that a problem needing attention goes forever ignored. Rather it means that ultmately arranging safe functional access may take more time, trouble, and special arrangements. And cost accordingly.

Readers should also see MOBILE HOME PLUMBING where we further discuss oil tanks, oil piping, and water heaters for mobile homes. Page top sketch courtesy of Carson Dunlop.

Question: Mobile home furnace not working

(Dec 14, 2012) Sean Newcomer said:

I have a brand new thermo pride furnace for my moble home it ran fine for two months the furnace started cylcling, it would burn then the fan would come on after a couple minutes the call to burn would shut off, then the fan would shut off a few mins later, upon fan going off the burner would cycle for heat again and the fan would come on heat would stop and so on. but the heat keeps climbing it doesn't stop

so i got ahold of the installer he told me it was the thermostat, i replaced it and still does the same its under warranty but i can't afford to pay a serve man 200.00 to come to tell me the problem. is it the burner control or is it the computer board can it be reset and how

Reply:

Sean,

IF the warm air output from a supply register is blowing right onto the room wall thermostat, then "the thermostat is the problem" could be a correct statement.

Otherwise I suspect a bad fan limit switch or improper installation of that control. For example, if the limit switch is mis-adjusted or if its sensor spring is binding, the system won't work properly.

Watch out: a fan limit switch that is bent, damaged, mis-handled, even mis-adjusted, can be dangerous, risking damage to the heating equipment or even a fire.

Diagnostic articles for heating problem troubleshooting are at More Reading below.

Question: fixing or replacing mobile home or doublewide ductwork invaded by rats

23 January 2015 Chuck said:
I have a doublewide mobile home with the air ducts in the cieling. A rat has gotten into the air duct and chewed insulation and now insulation is blowing through the vent. I am going to have a company put a camera up there to find the break so it can be fixed. My question is would it be easier for me once I knew exactly where the break was to just go in from the roof. It seems alot faster and less expensive than tearing out the cieling and replacing sheetrock, tape and bed and repainting, not to mention the mess in the house. What are your thoughts?

Reply:

Chuck,

If your doublewide has a conventional continuous metal roof over an inaccessible space then you won't do well trying to cut into the roof and you risk creating a point of future roof leaks. I'd be inclined to work from the interior. But then I haven't seen your home.

If there is an attic access (which some doublewides have) then of course it'd make sense to get into that space and remove and replace the ductwork and any contaminated insulation.

Further, if there were rats in the ductwork, you want to replace ALL of the ductwork and insulation where rats were nesting lest their pee and poop and other debris become a health concern later on.

Frequently Asked Questions (FAQs)

(Nov 1, 2011) sandra reddick said:
i have a 1996 moble home trailer and was wonder why it is so cold in the winter time a very hot in the summer. just learning that the moble home has no insulation in it,is that a home code violation.

(Jan 14, 2013) Anonymous said:
weird i hv the same problm i hv a 1968 mobl home it is terrible in the cold the summer is unbearable if u hv no ac units.. is it a violation?

Reply:

"Violation" is a tricky term Sandra and Anon as building code enforcement is ultimately up to local building officials. More confusion can arise because mobile homes, often built by manufacturers who assume their products must comply with building regulations across multiple states or provinces, build to model codes, and local building inspectors, knowing this, may not feel compelled or even able to inspect such homes for local code compliance.

Question: use a residential heating furnace in a manufactured home?

(Jan 30, 2014) Ray Cole said:
Can a house residential furnace be used in a manufactured home

Reply:

Ray,

if by manufactured home you mean like modular housing, not a MOBILE home (trailer home) then yes.

If you mean in a trailer home like the types shown in this article - it depends - on equipment size, space requirements, btu requirements etc. The heater must meet the required HUD specifications.

If you have a specific brand and model in question let me know and I'll research the specifics.

Certainly because space and combustion air and btu requirements are often different for a mobile home like the ones discussed here, we expect to see heating equipment designed for safe installation there.

I'd be very wary about just hooking something up without knowing the specifics as you could risk burning the place down or dangerous carbon monoxide hazards.

(Nov 4, 2014) Anonymous said:
to Ray Cole: No you can not use a residential furnace or air handler in a mobile home. mobile homes are under HUD guide lines. In the installation instructions of residential systems spells this out. most heating systems for mobile homes are down flow and Coleman, Intertherm, Mortex make mobile home heating systems.

However, If you decide to replace the system with a package unit they are compatible as long as they have a high static blower system. Mobile home duct systems are not design to maintain pressure the further you get from the source.

Question: some rooms in doublewide don't get adequate heat

(Oct 4, 2014) Kathy said:
I have a double-wide built in 2000, my bedroom and bath are in the back of the house and is always so cold from October through the winter/ spring months. The heater is in great condition and I have had an inspector from the gas company check for heat loss, but it hasn't helped. Could there be a problem under the house with the ventilation pipes and how much would something like that cost to get inspected? I have had electric heaters in those rooms since I bought the place newly built for me. I have also had the company that built the house come out, but I think they only checked the inside.

Reply:

Kathy

The least costly first step might be to ask your heating service company to check for a disconnected or blocked heating duct or a closed register or duct damper.

The check needs to include a complete survey of the ducting, including under the unit.

(Nov 4, 2014) Anonymous said:
Kathy, with double wides typically the heater sets on one half of the home and has a crossover duct to the far half. If your cold rooms are on that far half the air flow and temp is greatly reduced by the time it gets to your rooms. the easiest and first step is to regulate the supply grills on the half the heater sets on. Cutting almost off any bathrooms (usually the hottest rooms) if the grills are broke replace them, next regulate to at least half off all rooms closest to the heater.

If this does not get the desired results, I would inspect the cross over duct. It should be dead center of the furnace and at least 12" supply. also you can put a scoop (small piece of metal in those vents in the colder rooms to deflect air up. Lastly I would check the seal around the connection of the floor supply boot to the main trunk line it is where to pieces of metal duct join and reseal with foil tape.

Question: clicking noiser but no heat from my electric air conditioning / heating system

(Dec 13, 2014) Robert said:
I live on a double wide mobile home- have an electric air conditioning/heater system. Couple days ago the heater was working and now it does some click noise like is going to come on but do not come on. What could be the problem? Thanks

Reply:

Robert,

It sounds as if you have a heat pump that's not working. See the diagnostics at

inspectapedia.com/aircond/Air_Conditioner_Wont_Start.htm

If outdoor temperatures are too low for your heat pump to provide heat the problem could be failure of your backup heating system to operate. Look for a control board or relay failure.

...

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Technical Reviewers & References

Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com

John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: johncranor@verizon.net

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The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.

[1] Section 184 Indian Home Loan Guarantee Program, U.S. Department of Housing & Urban Development, web search 1/5/2012, original source: portal.hud.gov/hudportal/HUD?src=/program_offices/public_indian_housing/ih/homeownership/184 - Quoting:
The Section 184 Indian Home Loan Guarantee Program is a home mortgage specifically designed for American Indian and Alaska Native families, Alaska Villages, Tribes, or Tribally Designated Housing Entities. Section 184 loans can be used, both on and off native lands, for new construction, rehabilitation, purchase of an existing home, or refinance.
Also see Freddie Mac & Fannie Mae

[9] New York State: "Manufactured Homes: an installation guide for the code enforcement official," undated. [Div. of Code Enforcement & Admin. - 518-474-4073, George E. Clark, Jr., Director] - this is a guide tool, not an enforcement code or standard.

[16] Wikipedia provided background information about some topics discussed at this website provided this citation is also found in the same article along with a " retrieved on" date. NOTE: because Wikipedia entries are fluid and can be amended in real time, we cite the retrieval date of Wikipedia citations and we do not assert that the information found there is necessarily authoritative. - Entry on Mobile Homes, original source: http://en.wikipedia.org/wiki/Mobile_home#Regulation, retrieved 8/14/2012

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

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Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting:A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.